A simple marinade made in the blender with balsamic vinegar, olive oil, a bit of brown sugar, and fresh marjoram gives flavor to flank steak before it’s grilled. Save some of the marinade to mix into roasted bell peppers, and add chopped olives for a briny zing to the relish. Serve with greens drizzled with Creamy Peppercorn Dressing.
- 1Heat an outdoor grill to high (about 450°F to 550°F). Season the steak generously with salt and pepper and place it in a 13-by-9-inch baking dish.
- 2Place the remaining measured ingredients in a blender and blend until evenly combined, about 30 seconds. Remove 3 tablespoons of the marinade and set it aside for the relish.
- 3Pour the remaining marinade into the dish with the steak, turn the steak to coat, and let it marinate at room temperature for 30 minutes, flipping halfway through. Meanwhile, grill the peppers for the relish.
For the relish:
- 1Place the bell peppers on the grill. Cover the grill and cook, turning occasionally, until the peppers are blackened and blistered on all sides, about 25 minutes.
- 2Transfer the peppers to a large bowl. Cover tightly with plastic wrap or a large plate and let sit until cool enough to handle, about 15 minutes. Meanwhile, grill the steak.
To grill the steak:
- 1Remove the steak from the baking dish and let any excess marinade drip off; discard the marinade. Place the steak on the grill and season it generously with salt and pepper. Cover the grill and cook until grill marks appear on the bottom, about 5 to 6 minutes.
- 2Flip the steak and season generously with salt and pepper. Cover the grill and continue to cook until grill marks appear on the bottom and an instant-read thermometer inserted into the middle of the steak registers 125°F to 130°F for medium rare, about 5 to 6 minutes more. Transfer to a large, clean plate and let rest for 10 to 15 minutes. Meanwhile, finish the relish.
To finish the relish:
- 1Transfer the peppers from the bowl to a cutting board. Set the bowl aside, reserving any liquid inside. Use a knife to scrape and peel the skins off; discard the skins. Slice the peppers open and remove the seeds and membranes. Cut the peppers into medium dice and return them to the large bowl.
- 2Add the remaining measured ingredients and the reserved marinade and stir until evenly combined. Taste and season with salt and pepper as needed.
- 3Thinly slice the steak against the grain, season it with salt and pepper, and serve with the bell pepper relish.